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1/*
2 * kvm eventfd support - use eventfd objects to signal various KVM events
3 *
4 * Copyright 2009 Novell. All Rights Reserved.
5 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
6 *
7 * Author:
8 * Gregory Haskins <ghaskins@novell.com>
9 *
10 * This file is free software; you can redistribute it and/or modify
11 * it under the terms of version 2 of the GNU General Public License
12 * as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
22 */
23
24#include <linux/kvm_host.h>
25#include <linux/kvm.h>
26#include <linux/workqueue.h>
27#include <linux/syscalls.h>
28#include <linux/wait.h>
29#include <linux/poll.h>
30#include <linux/file.h>
31#include <linux/list.h>
32#include <linux/eventfd.h>
33#include <linux/kernel.h>
34#include <linux/slab.h>
35
36#include "iodev.h"
37
38/*
39 * --------------------------------------------------------------------
40 * irqfd: Allows an fd to be used to inject an interrupt to the guest
41 *
42 * Credit goes to Avi Kivity for the original idea.
43 * --------------------------------------------------------------------
44 */
45
46struct _irqfd {
47 /* Used for MSI fast-path */
48 struct kvm *kvm;
49 wait_queue_t wait;
50 /* Update side is protected by irqfds.lock */
51 struct kvm_kernel_irq_routing_entry __rcu *irq_entry;
52 /* Used for level IRQ fast-path */
53 int gsi;
54 struct work_struct inject;
55 /* Used for setup/shutdown */
56 struct eventfd_ctx *eventfd;
57 struct list_head list;
58 poll_table pt;
59 struct work_struct shutdown;
60};
61
62static struct workqueue_struct *irqfd_cleanup_wq;
63
64static void
65irqfd_inject(struct work_struct *work)
66{
67 struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
68 struct kvm *kvm = irqfd->kvm;
69
70 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
71 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
72}
73
74/*
75 * Race-free decouple logic (ordering is critical)
76 */
77static void
78irqfd_shutdown(struct work_struct *work)
79{
80 struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
81 u64 cnt;
82
83 /*
84 * Synchronize with the wait-queue and unhook ourselves to prevent
85 * further events.
86 */
87 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
88
89 /*
90 * We know no new events will be scheduled at this point, so block
91 * until all previously outstanding events have completed
92 */
93 flush_work_sync(&irqfd->inject);
94
95 /*
96 * It is now safe to release the object's resources
97 */
98 eventfd_ctx_put(irqfd->eventfd);
99 kfree(irqfd);
100}
101
102
103/* assumes kvm->irqfds.lock is held */
104static bool
105irqfd_is_active(struct _irqfd *irqfd)
106{
107 return list_empty(&irqfd->list) ? false : true;
108}
109
110/*
111 * Mark the irqfd as inactive and schedule it for removal
112 *
113 * assumes kvm->irqfds.lock is held
114 */
115static void
116irqfd_deactivate(struct _irqfd *irqfd)
117{
118 BUG_ON(!irqfd_is_active(irqfd));
119
120 list_del_init(&irqfd->list);
121
122 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
123}
124
125/*
126 * Called with wqh->lock held and interrupts disabled
127 */
128static int
129irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
130{
131 struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait);
132 unsigned long flags = (unsigned long)key;
133 struct kvm_kernel_irq_routing_entry *irq;
134 struct kvm *kvm = irqfd->kvm;
135
136 if (flags & POLLIN) {
137 rcu_read_lock();
138 irq = rcu_dereference(irqfd->irq_entry);
139 /* An event has been signaled, inject an interrupt */
140 if (irq)
141 kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
142 else
143 schedule_work(&irqfd->inject);
144 rcu_read_unlock();
145 }
146
147 if (flags & POLLHUP) {
148 /* The eventfd is closing, detach from KVM */
149 unsigned long flags;
150
151 spin_lock_irqsave(&kvm->irqfds.lock, flags);
152
153 /*
154 * We must check if someone deactivated the irqfd before
155 * we could acquire the irqfds.lock since the item is
156 * deactivated from the KVM side before it is unhooked from
157 * the wait-queue. If it is already deactivated, we can
158 * simply return knowing the other side will cleanup for us.
159 * We cannot race against the irqfd going away since the
160 * other side is required to acquire wqh->lock, which we hold
161 */
162 if (irqfd_is_active(irqfd))
163 irqfd_deactivate(irqfd);
164
165 spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
166 }
167
168 return 0;
169}
170
171static void
172irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
173 poll_table *pt)
174{
175 struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt);
176 add_wait_queue(wqh, &irqfd->wait);
177}
178
179/* Must be called under irqfds.lock */
180static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd,
181 struct kvm_irq_routing_table *irq_rt)
182{
183 struct kvm_kernel_irq_routing_entry *e;
184 struct hlist_node *n;
185
186 if (irqfd->gsi >= irq_rt->nr_rt_entries) {
187 rcu_assign_pointer(irqfd->irq_entry, NULL);
188 return;
189 }
190
191 hlist_for_each_entry(e, n, &irq_rt->map[irqfd->gsi], link) {
192 /* Only fast-path MSI. */
193 if (e->type == KVM_IRQ_ROUTING_MSI)
194 rcu_assign_pointer(irqfd->irq_entry, e);
195 else
196 rcu_assign_pointer(irqfd->irq_entry, NULL);
197 }
198}
199
200static int
201kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
202{
203 struct kvm_irq_routing_table *irq_rt;
204 struct _irqfd *irqfd, *tmp;
205 struct file *file = NULL;
206 struct eventfd_ctx *eventfd = NULL;
207 int ret;
208 unsigned int events;
209
210 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
211 if (!irqfd)
212 return -ENOMEM;
213
214 irqfd->kvm = kvm;
215 irqfd->gsi = gsi;
216 INIT_LIST_HEAD(&irqfd->list);
217 INIT_WORK(&irqfd->inject, irqfd_inject);
218 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
219
220 file = eventfd_fget(fd);
221 if (IS_ERR(file)) {
222 ret = PTR_ERR(file);
223 goto fail;
224 }
225
226 eventfd = eventfd_ctx_fileget(file);
227 if (IS_ERR(eventfd)) {
228 ret = PTR_ERR(eventfd);
229 goto fail;
230 }
231
232 irqfd->eventfd = eventfd;
233
234 /*
235 * Install our own custom wake-up handling so we are notified via
236 * a callback whenever someone signals the underlying eventfd
237 */
238 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
239 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
240
241 spin_lock_irq(&kvm->irqfds.lock);
242
243 ret = 0;
244 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
245 if (irqfd->eventfd != tmp->eventfd)
246 continue;
247 /* This fd is used for another irq already. */
248 ret = -EBUSY;
249 spin_unlock_irq(&kvm->irqfds.lock);
250 goto fail;
251 }
252
253 irq_rt = rcu_dereference_protected(kvm->irq_routing,
254 lockdep_is_held(&kvm->irqfds.lock));
255 irqfd_update(kvm, irqfd, irq_rt);
256
257 events = file->f_op->poll(file, &irqfd->pt);
258
259 list_add_tail(&irqfd->list, &kvm->irqfds.items);
260
261 /*
262 * Check if there was an event already pending on the eventfd
263 * before we registered, and trigger it as if we didn't miss it.
264 */
265 if (events & POLLIN)
266 schedule_work(&irqfd->inject);
267
268 spin_unlock_irq(&kvm->irqfds.lock);
269
270 /*
271 * do not drop the file until the irqfd is fully initialized, otherwise
272 * we might race against the POLLHUP
273 */
274 fput(file);
275
276 return 0;
277
278fail:
279 if (eventfd && !IS_ERR(eventfd))
280 eventfd_ctx_put(eventfd);
281
282 if (!IS_ERR(file))
283 fput(file);
284
285 kfree(irqfd);
286 return ret;
287}
288
289void
290kvm_eventfd_init(struct kvm *kvm)
291{
292 spin_lock_init(&kvm->irqfds.lock);
293 INIT_LIST_HEAD(&kvm->irqfds.items);
294 INIT_LIST_HEAD(&kvm->ioeventfds);
295}
296
297/*
298 * shutdown any irqfd's that match fd+gsi
299 */
300static int
301kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi)
302{
303 struct _irqfd *irqfd, *tmp;
304 struct eventfd_ctx *eventfd;
305
306 eventfd = eventfd_ctx_fdget(fd);
307 if (IS_ERR(eventfd))
308 return PTR_ERR(eventfd);
309
310 spin_lock_irq(&kvm->irqfds.lock);
311
312 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
313 if (irqfd->eventfd == eventfd && irqfd->gsi == gsi) {
314 /*
315 * This rcu_assign_pointer is needed for when
316 * another thread calls kvm_irq_routing_update before
317 * we flush workqueue below (we synchronize with
318 * kvm_irq_routing_update using irqfds.lock).
319 * It is paired with synchronize_rcu done by caller
320 * of that function.
321 */
322 rcu_assign_pointer(irqfd->irq_entry, NULL);
323 irqfd_deactivate(irqfd);
324 }
325 }
326
327 spin_unlock_irq(&kvm->irqfds.lock);
328 eventfd_ctx_put(eventfd);
329
330 /*
331 * Block until we know all outstanding shutdown jobs have completed
332 * so that we guarantee there will not be any more interrupts on this
333 * gsi once this deassign function returns.
334 */
335 flush_workqueue(irqfd_cleanup_wq);
336
337 return 0;
338}
339
340int
341kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)
342{
343 if (flags & KVM_IRQFD_FLAG_DEASSIGN)
344 return kvm_irqfd_deassign(kvm, fd, gsi);
345
346 return kvm_irqfd_assign(kvm, fd, gsi);
347}
348
349/*
350 * This function is called as the kvm VM fd is being released. Shutdown all
351 * irqfds that still remain open
352 */
353void
354kvm_irqfd_release(struct kvm *kvm)
355{
356 struct _irqfd *irqfd, *tmp;
357
358 spin_lock_irq(&kvm->irqfds.lock);
359
360 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
361 irqfd_deactivate(irqfd);
362
363 spin_unlock_irq(&kvm->irqfds.lock);
364
365 /*
366 * Block until we know all outstanding shutdown jobs have completed
367 * since we do not take a kvm* reference.
368 */
369 flush_workqueue(irqfd_cleanup_wq);
370
371}
372
373/*
374 * Change irq_routing and irqfd.
375 * Caller must invoke synchronize_rcu afterwards.
376 */
377void kvm_irq_routing_update(struct kvm *kvm,
378 struct kvm_irq_routing_table *irq_rt)
379{
380 struct _irqfd *irqfd;
381
382 spin_lock_irq(&kvm->irqfds.lock);
383
384 rcu_assign_pointer(kvm->irq_routing, irq_rt);
385
386 list_for_each_entry(irqfd, &kvm->irqfds.items, list)
387 irqfd_update(kvm, irqfd, irq_rt);
388
389 spin_unlock_irq(&kvm->irqfds.lock);
390}
391
392/*
393 * create a host-wide workqueue for issuing deferred shutdown requests
394 * aggregated from all vm* instances. We need our own isolated single-thread
395 * queue to prevent deadlock against flushing the normal work-queue.
396 */
397static int __init irqfd_module_init(void)
398{
399 irqfd_cleanup_wq = create_singlethread_workqueue("kvm-irqfd-cleanup");
400 if (!irqfd_cleanup_wq)
401 return -ENOMEM;
402
403 return 0;
404}
405
406static void __exit irqfd_module_exit(void)
407{
408 destroy_workqueue(irqfd_cleanup_wq);
409}
410
411module_init(irqfd_module_init);
412module_exit(irqfd_module_exit);
413
414/*
415 * --------------------------------------------------------------------
416 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
417 *
418 * userspace can register a PIO/MMIO address with an eventfd for receiving
419 * notification when the memory has been touched.
420 * --------------------------------------------------------------------
421 */
422
423struct _ioeventfd {
424 struct list_head list;
425 u64 addr;
426 int length;
427 struct eventfd_ctx *eventfd;
428 u64 datamatch;
429 struct kvm_io_device dev;
430 bool wildcard;
431};
432
433static inline struct _ioeventfd *
434to_ioeventfd(struct kvm_io_device *dev)
435{
436 return container_of(dev, struct _ioeventfd, dev);
437}
438
439static void
440ioeventfd_release(struct _ioeventfd *p)
441{
442 eventfd_ctx_put(p->eventfd);
443 list_del(&p->list);
444 kfree(p);
445}
446
447static bool
448ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
449{
450 u64 _val;
451
452 if (!(addr == p->addr && len == p->length))
453 /* address-range must be precise for a hit */
454 return false;
455
456 if (p->wildcard)
457 /* all else equal, wildcard is always a hit */
458 return true;
459
460 /* otherwise, we have to actually compare the data */
461
462 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
463
464 switch (len) {
465 case 1:
466 _val = *(u8 *)val;
467 break;
468 case 2:
469 _val = *(u16 *)val;
470 break;
471 case 4:
472 _val = *(u32 *)val;
473 break;
474 case 8:
475 _val = *(u64 *)val;
476 break;
477 default:
478 return false;
479 }
480
481 return _val == p->datamatch ? true : false;
482}
483
484/* MMIO/PIO writes trigger an event if the addr/val match */
485static int
486ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
487 const void *val)
488{
489 struct _ioeventfd *p = to_ioeventfd(this);
490
491 if (!ioeventfd_in_range(p, addr, len, val))
492 return -EOPNOTSUPP;
493
494 eventfd_signal(p->eventfd, 1);
495 return 0;
496}
497
498/*
499 * This function is called as KVM is completely shutting down. We do not
500 * need to worry about locking just nuke anything we have as quickly as possible
501 */
502static void
503ioeventfd_destructor(struct kvm_io_device *this)
504{
505 struct _ioeventfd *p = to_ioeventfd(this);
506
507 ioeventfd_release(p);
508}
509
510static const struct kvm_io_device_ops ioeventfd_ops = {
511 .write = ioeventfd_write,
512 .destructor = ioeventfd_destructor,
513};
514
515/* assumes kvm->slots_lock held */
516static bool
517ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
518{
519 struct _ioeventfd *_p;
520
521 list_for_each_entry(_p, &kvm->ioeventfds, list)
522 if (_p->addr == p->addr && _p->length == p->length &&
523 (_p->wildcard || p->wildcard ||
524 _p->datamatch == p->datamatch))
525 return true;
526
527 return false;
528}
529
530static int
531kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
532{
533 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
534 enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
535 struct _ioeventfd *p;
536 struct eventfd_ctx *eventfd;
537 int ret;
538
539 /* must be natural-word sized */
540 switch (args->len) {
541 case 1:
542 case 2:
543 case 4:
544 case 8:
545 break;
546 default:
547 return -EINVAL;
548 }
549
550 /* check for range overflow */
551 if (args->addr + args->len < args->addr)
552 return -EINVAL;
553
554 /* check for extra flags that we don't understand */
555 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
556 return -EINVAL;
557
558 eventfd = eventfd_ctx_fdget(args->fd);
559 if (IS_ERR(eventfd))
560 return PTR_ERR(eventfd);
561
562 p = kzalloc(sizeof(*p), GFP_KERNEL);
563 if (!p) {
564 ret = -ENOMEM;
565 goto fail;
566 }
567
568 INIT_LIST_HEAD(&p->list);
569 p->addr = args->addr;
570 p->length = args->len;
571 p->eventfd = eventfd;
572
573 /* The datamatch feature is optional, otherwise this is a wildcard */
574 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
575 p->datamatch = args->datamatch;
576 else
577 p->wildcard = true;
578
579 mutex_lock(&kvm->slots_lock);
580
581 /* Verify that there isn't a match already */
582 if (ioeventfd_check_collision(kvm, p)) {
583 ret = -EEXIST;
584 goto unlock_fail;
585 }
586
587 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
588
589 ret = kvm_io_bus_register_dev(kvm, bus_idx, &p->dev);
590 if (ret < 0)
591 goto unlock_fail;
592
593 list_add_tail(&p->list, &kvm->ioeventfds);
594
595 mutex_unlock(&kvm->slots_lock);
596
597 return 0;
598
599unlock_fail:
600 mutex_unlock(&kvm->slots_lock);
601
602fail:
603 kfree(p);
604 eventfd_ctx_put(eventfd);
605
606 return ret;
607}
608
609static int
610kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
611{
612 int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
613 enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
614 struct _ioeventfd *p, *tmp;
615 struct eventfd_ctx *eventfd;
616 int ret = -ENOENT;
617
618 eventfd = eventfd_ctx_fdget(args->fd);
619 if (IS_ERR(eventfd))
620 return PTR_ERR(eventfd);
621
622 mutex_lock(&kvm->slots_lock);
623
624 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
625 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
626
627 if (p->eventfd != eventfd ||
628 p->addr != args->addr ||
629 p->length != args->len ||
630 p->wildcard != wildcard)
631 continue;
632
633 if (!p->wildcard && p->datamatch != args->datamatch)
634 continue;
635
636 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
637 ioeventfd_release(p);
638 ret = 0;
639 break;
640 }
641
642 mutex_unlock(&kvm->slots_lock);
643
644 eventfd_ctx_put(eventfd);
645
646 return ret;
647}
648
649int
650kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
651{
652 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
653 return kvm_deassign_ioeventfd(kvm, args);
654
655 return kvm_assign_ioeventfd(kvm, args);
656}
1/*
2 * kvm eventfd support - use eventfd objects to signal various KVM events
3 *
4 * Copyright 2009 Novell. All Rights Reserved.
5 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
6 *
7 * Author:
8 * Gregory Haskins <ghaskins@novell.com>
9 *
10 * This file is free software; you can redistribute it and/or modify
11 * it under the terms of version 2 of the GNU General Public License
12 * as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
22 */
23
24#include <linux/kvm_host.h>
25#include <linux/kvm.h>
26#include <linux/kvm_irqfd.h>
27#include <linux/workqueue.h>
28#include <linux/syscalls.h>
29#include <linux/wait.h>
30#include <linux/poll.h>
31#include <linux/file.h>
32#include <linux/list.h>
33#include <linux/eventfd.h>
34#include <linux/kernel.h>
35#include <linux/srcu.h>
36#include <linux/slab.h>
37#include <linux/seqlock.h>
38#include <linux/irqbypass.h>
39#include <trace/events/kvm.h>
40
41#include <kvm/iodev.h>
42
43#ifdef CONFIG_HAVE_KVM_IRQFD
44
45static struct workqueue_struct *irqfd_cleanup_wq;
46
47static void
48irqfd_inject(struct work_struct *work)
49{
50 struct kvm_kernel_irqfd *irqfd =
51 container_of(work, struct kvm_kernel_irqfd, inject);
52 struct kvm *kvm = irqfd->kvm;
53
54 if (!irqfd->resampler) {
55 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
56 false);
57 kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
58 false);
59 } else
60 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
61 irqfd->gsi, 1, false);
62}
63
64/*
65 * Since resampler irqfds share an IRQ source ID, we de-assert once
66 * then notify all of the resampler irqfds using this GSI. We can't
67 * do multiple de-asserts or we risk racing with incoming re-asserts.
68 */
69static void
70irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
71{
72 struct kvm_kernel_irqfd_resampler *resampler;
73 struct kvm *kvm;
74 struct kvm_kernel_irqfd *irqfd;
75 int idx;
76
77 resampler = container_of(kian,
78 struct kvm_kernel_irqfd_resampler, notifier);
79 kvm = resampler->kvm;
80
81 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
82 resampler->notifier.gsi, 0, false);
83
84 idx = srcu_read_lock(&kvm->irq_srcu);
85
86 list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link)
87 eventfd_signal(irqfd->resamplefd, 1);
88
89 srcu_read_unlock(&kvm->irq_srcu, idx);
90}
91
92static void
93irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
94{
95 struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
96 struct kvm *kvm = resampler->kvm;
97
98 mutex_lock(&kvm->irqfds.resampler_lock);
99
100 list_del_rcu(&irqfd->resampler_link);
101 synchronize_srcu(&kvm->irq_srcu);
102
103 if (list_empty(&resampler->list)) {
104 list_del(&resampler->link);
105 kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
106 kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
107 resampler->notifier.gsi, 0, false);
108 kfree(resampler);
109 }
110
111 mutex_unlock(&kvm->irqfds.resampler_lock);
112}
113
114/*
115 * Race-free decouple logic (ordering is critical)
116 */
117static void
118irqfd_shutdown(struct work_struct *work)
119{
120 struct kvm_kernel_irqfd *irqfd =
121 container_of(work, struct kvm_kernel_irqfd, shutdown);
122 u64 cnt;
123
124 /*
125 * Synchronize with the wait-queue and unhook ourselves to prevent
126 * further events.
127 */
128 eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
129
130 /*
131 * We know no new events will be scheduled at this point, so block
132 * until all previously outstanding events have completed
133 */
134 flush_work(&irqfd->inject);
135
136 if (irqfd->resampler) {
137 irqfd_resampler_shutdown(irqfd);
138 eventfd_ctx_put(irqfd->resamplefd);
139 }
140
141 /*
142 * It is now safe to release the object's resources
143 */
144#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
145 irq_bypass_unregister_consumer(&irqfd->consumer);
146#endif
147 eventfd_ctx_put(irqfd->eventfd);
148 kfree(irqfd);
149}
150
151
152/* assumes kvm->irqfds.lock is held */
153static bool
154irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
155{
156 return list_empty(&irqfd->list) ? false : true;
157}
158
159/*
160 * Mark the irqfd as inactive and schedule it for removal
161 *
162 * assumes kvm->irqfds.lock is held
163 */
164static void
165irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
166{
167 BUG_ON(!irqfd_is_active(irqfd));
168
169 list_del_init(&irqfd->list);
170
171 queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
172}
173
174int __attribute__((weak)) kvm_arch_set_irq_inatomic(
175 struct kvm_kernel_irq_routing_entry *irq,
176 struct kvm *kvm, int irq_source_id,
177 int level,
178 bool line_status)
179{
180 return -EWOULDBLOCK;
181}
182
183/*
184 * Called with wqh->lock held and interrupts disabled
185 */
186static int
187irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
188{
189 struct kvm_kernel_irqfd *irqfd =
190 container_of(wait, struct kvm_kernel_irqfd, wait);
191 __poll_t flags = key_to_poll(key);
192 struct kvm_kernel_irq_routing_entry irq;
193 struct kvm *kvm = irqfd->kvm;
194 unsigned seq;
195 int idx;
196
197 if (flags & EPOLLIN) {
198 idx = srcu_read_lock(&kvm->irq_srcu);
199 do {
200 seq = read_seqcount_begin(&irqfd->irq_entry_sc);
201 irq = irqfd->irq_entry;
202 } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
203 /* An event has been signaled, inject an interrupt */
204 if (kvm_arch_set_irq_inatomic(&irq, kvm,
205 KVM_USERSPACE_IRQ_SOURCE_ID, 1,
206 false) == -EWOULDBLOCK)
207 schedule_work(&irqfd->inject);
208 srcu_read_unlock(&kvm->irq_srcu, idx);
209 }
210
211 if (flags & EPOLLHUP) {
212 /* The eventfd is closing, detach from KVM */
213 unsigned long flags;
214
215 spin_lock_irqsave(&kvm->irqfds.lock, flags);
216
217 /*
218 * We must check if someone deactivated the irqfd before
219 * we could acquire the irqfds.lock since the item is
220 * deactivated from the KVM side before it is unhooked from
221 * the wait-queue. If it is already deactivated, we can
222 * simply return knowing the other side will cleanup for us.
223 * We cannot race against the irqfd going away since the
224 * other side is required to acquire wqh->lock, which we hold
225 */
226 if (irqfd_is_active(irqfd))
227 irqfd_deactivate(irqfd);
228
229 spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
230 }
231
232 return 0;
233}
234
235static void
236irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
237 poll_table *pt)
238{
239 struct kvm_kernel_irqfd *irqfd =
240 container_of(pt, struct kvm_kernel_irqfd, pt);
241 add_wait_queue(wqh, &irqfd->wait);
242}
243
244/* Must be called under irqfds.lock */
245static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
246{
247 struct kvm_kernel_irq_routing_entry *e;
248 struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
249 int n_entries;
250
251 n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
252
253 write_seqcount_begin(&irqfd->irq_entry_sc);
254
255 e = entries;
256 if (n_entries == 1)
257 irqfd->irq_entry = *e;
258 else
259 irqfd->irq_entry.type = 0;
260
261 write_seqcount_end(&irqfd->irq_entry_sc);
262}
263
264#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
265void __attribute__((weak)) kvm_arch_irq_bypass_stop(
266 struct irq_bypass_consumer *cons)
267{
268}
269
270void __attribute__((weak)) kvm_arch_irq_bypass_start(
271 struct irq_bypass_consumer *cons)
272{
273}
274
275int __attribute__((weak)) kvm_arch_update_irqfd_routing(
276 struct kvm *kvm, unsigned int host_irq,
277 uint32_t guest_irq, bool set)
278{
279 return 0;
280}
281#endif
282
283static int
284kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
285{
286 struct kvm_kernel_irqfd *irqfd, *tmp;
287 struct fd f;
288 struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
289 int ret;
290 __poll_t events;
291 int idx;
292
293 if (!kvm_arch_intc_initialized(kvm))
294 return -EAGAIN;
295
296 irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
297 if (!irqfd)
298 return -ENOMEM;
299
300 irqfd->kvm = kvm;
301 irqfd->gsi = args->gsi;
302 INIT_LIST_HEAD(&irqfd->list);
303 INIT_WORK(&irqfd->inject, irqfd_inject);
304 INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
305 seqcount_init(&irqfd->irq_entry_sc);
306
307 f = fdget(args->fd);
308 if (!f.file) {
309 ret = -EBADF;
310 goto out;
311 }
312
313 eventfd = eventfd_ctx_fileget(f.file);
314 if (IS_ERR(eventfd)) {
315 ret = PTR_ERR(eventfd);
316 goto fail;
317 }
318
319 irqfd->eventfd = eventfd;
320
321 if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
322 struct kvm_kernel_irqfd_resampler *resampler;
323
324 resamplefd = eventfd_ctx_fdget(args->resamplefd);
325 if (IS_ERR(resamplefd)) {
326 ret = PTR_ERR(resamplefd);
327 goto fail;
328 }
329
330 irqfd->resamplefd = resamplefd;
331 INIT_LIST_HEAD(&irqfd->resampler_link);
332
333 mutex_lock(&kvm->irqfds.resampler_lock);
334
335 list_for_each_entry(resampler,
336 &kvm->irqfds.resampler_list, link) {
337 if (resampler->notifier.gsi == irqfd->gsi) {
338 irqfd->resampler = resampler;
339 break;
340 }
341 }
342
343 if (!irqfd->resampler) {
344 resampler = kzalloc(sizeof(*resampler), GFP_KERNEL);
345 if (!resampler) {
346 ret = -ENOMEM;
347 mutex_unlock(&kvm->irqfds.resampler_lock);
348 goto fail;
349 }
350
351 resampler->kvm = kvm;
352 INIT_LIST_HEAD(&resampler->list);
353 resampler->notifier.gsi = irqfd->gsi;
354 resampler->notifier.irq_acked = irqfd_resampler_ack;
355 INIT_LIST_HEAD(&resampler->link);
356
357 list_add(&resampler->link, &kvm->irqfds.resampler_list);
358 kvm_register_irq_ack_notifier(kvm,
359 &resampler->notifier);
360 irqfd->resampler = resampler;
361 }
362
363 list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
364 synchronize_srcu(&kvm->irq_srcu);
365
366 mutex_unlock(&kvm->irqfds.resampler_lock);
367 }
368
369 /*
370 * Install our own custom wake-up handling so we are notified via
371 * a callback whenever someone signals the underlying eventfd
372 */
373 init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
374 init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
375
376 spin_lock_irq(&kvm->irqfds.lock);
377
378 ret = 0;
379 list_for_each_entry(tmp, &kvm->irqfds.items, list) {
380 if (irqfd->eventfd != tmp->eventfd)
381 continue;
382 /* This fd is used for another irq already. */
383 ret = -EBUSY;
384 spin_unlock_irq(&kvm->irqfds.lock);
385 goto fail;
386 }
387
388 idx = srcu_read_lock(&kvm->irq_srcu);
389 irqfd_update(kvm, irqfd);
390 srcu_read_unlock(&kvm->irq_srcu, idx);
391
392 list_add_tail(&irqfd->list, &kvm->irqfds.items);
393
394 spin_unlock_irq(&kvm->irqfds.lock);
395
396 /*
397 * Check if there was an event already pending on the eventfd
398 * before we registered, and trigger it as if we didn't miss it.
399 */
400 events = f.file->f_op->poll(f.file, &irqfd->pt);
401
402 if (events & EPOLLIN)
403 schedule_work(&irqfd->inject);
404
405 /*
406 * do not drop the file until the irqfd is fully initialized, otherwise
407 * we might race against the EPOLLHUP
408 */
409 fdput(f);
410#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
411 if (kvm_arch_has_irq_bypass()) {
412 irqfd->consumer.token = (void *)irqfd->eventfd;
413 irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
414 irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
415 irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
416 irqfd->consumer.start = kvm_arch_irq_bypass_start;
417 ret = irq_bypass_register_consumer(&irqfd->consumer);
418 if (ret)
419 pr_info("irq bypass consumer (token %p) registration fails: %d\n",
420 irqfd->consumer.token, ret);
421 }
422#endif
423
424 return 0;
425
426fail:
427 if (irqfd->resampler)
428 irqfd_resampler_shutdown(irqfd);
429
430 if (resamplefd && !IS_ERR(resamplefd))
431 eventfd_ctx_put(resamplefd);
432
433 if (eventfd && !IS_ERR(eventfd))
434 eventfd_ctx_put(eventfd);
435
436 fdput(f);
437
438out:
439 kfree(irqfd);
440 return ret;
441}
442
443bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
444{
445 struct kvm_irq_ack_notifier *kian;
446 int gsi, idx;
447
448 idx = srcu_read_lock(&kvm->irq_srcu);
449 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
450 if (gsi != -1)
451 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
452 link)
453 if (kian->gsi == gsi) {
454 srcu_read_unlock(&kvm->irq_srcu, idx);
455 return true;
456 }
457
458 srcu_read_unlock(&kvm->irq_srcu, idx);
459
460 return false;
461}
462EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
463
464void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
465{
466 struct kvm_irq_ack_notifier *kian;
467
468 hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
469 link)
470 if (kian->gsi == gsi)
471 kian->irq_acked(kian);
472}
473
474void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
475{
476 int gsi, idx;
477
478 trace_kvm_ack_irq(irqchip, pin);
479
480 idx = srcu_read_lock(&kvm->irq_srcu);
481 gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
482 if (gsi != -1)
483 kvm_notify_acked_gsi(kvm, gsi);
484 srcu_read_unlock(&kvm->irq_srcu, idx);
485}
486
487void kvm_register_irq_ack_notifier(struct kvm *kvm,
488 struct kvm_irq_ack_notifier *kian)
489{
490 mutex_lock(&kvm->irq_lock);
491 hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
492 mutex_unlock(&kvm->irq_lock);
493 kvm_arch_post_irq_ack_notifier_list_update(kvm);
494}
495
496void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
497 struct kvm_irq_ack_notifier *kian)
498{
499 mutex_lock(&kvm->irq_lock);
500 hlist_del_init_rcu(&kian->link);
501 mutex_unlock(&kvm->irq_lock);
502 synchronize_srcu(&kvm->irq_srcu);
503 kvm_arch_post_irq_ack_notifier_list_update(kvm);
504}
505#endif
506
507void
508kvm_eventfd_init(struct kvm *kvm)
509{
510#ifdef CONFIG_HAVE_KVM_IRQFD
511 spin_lock_init(&kvm->irqfds.lock);
512 INIT_LIST_HEAD(&kvm->irqfds.items);
513 INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
514 mutex_init(&kvm->irqfds.resampler_lock);
515#endif
516 INIT_LIST_HEAD(&kvm->ioeventfds);
517}
518
519#ifdef CONFIG_HAVE_KVM_IRQFD
520/*
521 * shutdown any irqfd's that match fd+gsi
522 */
523static int
524kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
525{
526 struct kvm_kernel_irqfd *irqfd, *tmp;
527 struct eventfd_ctx *eventfd;
528
529 eventfd = eventfd_ctx_fdget(args->fd);
530 if (IS_ERR(eventfd))
531 return PTR_ERR(eventfd);
532
533 spin_lock_irq(&kvm->irqfds.lock);
534
535 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
536 if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
537 /*
538 * This clearing of irq_entry.type is needed for when
539 * another thread calls kvm_irq_routing_update before
540 * we flush workqueue below (we synchronize with
541 * kvm_irq_routing_update using irqfds.lock).
542 */
543 write_seqcount_begin(&irqfd->irq_entry_sc);
544 irqfd->irq_entry.type = 0;
545 write_seqcount_end(&irqfd->irq_entry_sc);
546 irqfd_deactivate(irqfd);
547 }
548 }
549
550 spin_unlock_irq(&kvm->irqfds.lock);
551 eventfd_ctx_put(eventfd);
552
553 /*
554 * Block until we know all outstanding shutdown jobs have completed
555 * so that we guarantee there will not be any more interrupts on this
556 * gsi once this deassign function returns.
557 */
558 flush_workqueue(irqfd_cleanup_wq);
559
560 return 0;
561}
562
563int
564kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
565{
566 if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
567 return -EINVAL;
568
569 if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
570 return kvm_irqfd_deassign(kvm, args);
571
572 return kvm_irqfd_assign(kvm, args);
573}
574
575/*
576 * This function is called as the kvm VM fd is being released. Shutdown all
577 * irqfds that still remain open
578 */
579void
580kvm_irqfd_release(struct kvm *kvm)
581{
582 struct kvm_kernel_irqfd *irqfd, *tmp;
583
584 spin_lock_irq(&kvm->irqfds.lock);
585
586 list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
587 irqfd_deactivate(irqfd);
588
589 spin_unlock_irq(&kvm->irqfds.lock);
590
591 /*
592 * Block until we know all outstanding shutdown jobs have completed
593 * since we do not take a kvm* reference.
594 */
595 flush_workqueue(irqfd_cleanup_wq);
596
597}
598
599/*
600 * Take note of a change in irq routing.
601 * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
602 */
603void kvm_irq_routing_update(struct kvm *kvm)
604{
605 struct kvm_kernel_irqfd *irqfd;
606
607 spin_lock_irq(&kvm->irqfds.lock);
608
609 list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
610 irqfd_update(kvm, irqfd);
611
612#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
613 if (irqfd->producer) {
614 int ret = kvm_arch_update_irqfd_routing(
615 irqfd->kvm, irqfd->producer->irq,
616 irqfd->gsi, 1);
617 WARN_ON(ret);
618 }
619#endif
620 }
621
622 spin_unlock_irq(&kvm->irqfds.lock);
623}
624
625/*
626 * create a host-wide workqueue for issuing deferred shutdown requests
627 * aggregated from all vm* instances. We need our own isolated
628 * queue to ease flushing work items when a VM exits.
629 */
630int kvm_irqfd_init(void)
631{
632 irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
633 if (!irqfd_cleanup_wq)
634 return -ENOMEM;
635
636 return 0;
637}
638
639void kvm_irqfd_exit(void)
640{
641 destroy_workqueue(irqfd_cleanup_wq);
642}
643#endif
644
645/*
646 * --------------------------------------------------------------------
647 * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
648 *
649 * userspace can register a PIO/MMIO address with an eventfd for receiving
650 * notification when the memory has been touched.
651 * --------------------------------------------------------------------
652 */
653
654struct _ioeventfd {
655 struct list_head list;
656 u64 addr;
657 int length;
658 struct eventfd_ctx *eventfd;
659 u64 datamatch;
660 struct kvm_io_device dev;
661 u8 bus_idx;
662 bool wildcard;
663};
664
665static inline struct _ioeventfd *
666to_ioeventfd(struct kvm_io_device *dev)
667{
668 return container_of(dev, struct _ioeventfd, dev);
669}
670
671static void
672ioeventfd_release(struct _ioeventfd *p)
673{
674 eventfd_ctx_put(p->eventfd);
675 list_del(&p->list);
676 kfree(p);
677}
678
679static bool
680ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
681{
682 u64 _val;
683
684 if (addr != p->addr)
685 /* address must be precise for a hit */
686 return false;
687
688 if (!p->length)
689 /* length = 0 means only look at the address, so always a hit */
690 return true;
691
692 if (len != p->length)
693 /* address-range must be precise for a hit */
694 return false;
695
696 if (p->wildcard)
697 /* all else equal, wildcard is always a hit */
698 return true;
699
700 /* otherwise, we have to actually compare the data */
701
702 BUG_ON(!IS_ALIGNED((unsigned long)val, len));
703
704 switch (len) {
705 case 1:
706 _val = *(u8 *)val;
707 break;
708 case 2:
709 _val = *(u16 *)val;
710 break;
711 case 4:
712 _val = *(u32 *)val;
713 break;
714 case 8:
715 _val = *(u64 *)val;
716 break;
717 default:
718 return false;
719 }
720
721 return _val == p->datamatch ? true : false;
722}
723
724/* MMIO/PIO writes trigger an event if the addr/val match */
725static int
726ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
727 int len, const void *val)
728{
729 struct _ioeventfd *p = to_ioeventfd(this);
730
731 if (!ioeventfd_in_range(p, addr, len, val))
732 return -EOPNOTSUPP;
733
734 eventfd_signal(p->eventfd, 1);
735 return 0;
736}
737
738/*
739 * This function is called as KVM is completely shutting down. We do not
740 * need to worry about locking just nuke anything we have as quickly as possible
741 */
742static void
743ioeventfd_destructor(struct kvm_io_device *this)
744{
745 struct _ioeventfd *p = to_ioeventfd(this);
746
747 ioeventfd_release(p);
748}
749
750static const struct kvm_io_device_ops ioeventfd_ops = {
751 .write = ioeventfd_write,
752 .destructor = ioeventfd_destructor,
753};
754
755/* assumes kvm->slots_lock held */
756static bool
757ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
758{
759 struct _ioeventfd *_p;
760
761 list_for_each_entry(_p, &kvm->ioeventfds, list)
762 if (_p->bus_idx == p->bus_idx &&
763 _p->addr == p->addr &&
764 (!_p->length || !p->length ||
765 (_p->length == p->length &&
766 (_p->wildcard || p->wildcard ||
767 _p->datamatch == p->datamatch))))
768 return true;
769
770 return false;
771}
772
773static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
774{
775 if (flags & KVM_IOEVENTFD_FLAG_PIO)
776 return KVM_PIO_BUS;
777 if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
778 return KVM_VIRTIO_CCW_NOTIFY_BUS;
779 return KVM_MMIO_BUS;
780}
781
782static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
783 enum kvm_bus bus_idx,
784 struct kvm_ioeventfd *args)
785{
786
787 struct eventfd_ctx *eventfd;
788 struct _ioeventfd *p;
789 int ret;
790
791 eventfd = eventfd_ctx_fdget(args->fd);
792 if (IS_ERR(eventfd))
793 return PTR_ERR(eventfd);
794
795 p = kzalloc(sizeof(*p), GFP_KERNEL);
796 if (!p) {
797 ret = -ENOMEM;
798 goto fail;
799 }
800
801 INIT_LIST_HEAD(&p->list);
802 p->addr = args->addr;
803 p->bus_idx = bus_idx;
804 p->length = args->len;
805 p->eventfd = eventfd;
806
807 /* The datamatch feature is optional, otherwise this is a wildcard */
808 if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
809 p->datamatch = args->datamatch;
810 else
811 p->wildcard = true;
812
813 mutex_lock(&kvm->slots_lock);
814
815 /* Verify that there isn't a match already */
816 if (ioeventfd_check_collision(kvm, p)) {
817 ret = -EEXIST;
818 goto unlock_fail;
819 }
820
821 kvm_iodevice_init(&p->dev, &ioeventfd_ops);
822
823 ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
824 &p->dev);
825 if (ret < 0)
826 goto unlock_fail;
827
828 kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
829 list_add_tail(&p->list, &kvm->ioeventfds);
830
831 mutex_unlock(&kvm->slots_lock);
832
833 return 0;
834
835unlock_fail:
836 mutex_unlock(&kvm->slots_lock);
837
838fail:
839 kfree(p);
840 eventfd_ctx_put(eventfd);
841
842 return ret;
843}
844
845static int
846kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
847 struct kvm_ioeventfd *args)
848{
849 struct _ioeventfd *p, *tmp;
850 struct eventfd_ctx *eventfd;
851 struct kvm_io_bus *bus;
852 int ret = -ENOENT;
853
854 eventfd = eventfd_ctx_fdget(args->fd);
855 if (IS_ERR(eventfd))
856 return PTR_ERR(eventfd);
857
858 mutex_lock(&kvm->slots_lock);
859
860 list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
861 bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
862
863 if (p->bus_idx != bus_idx ||
864 p->eventfd != eventfd ||
865 p->addr != args->addr ||
866 p->length != args->len ||
867 p->wildcard != wildcard)
868 continue;
869
870 if (!p->wildcard && p->datamatch != args->datamatch)
871 continue;
872
873 kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
874 bus = kvm_get_bus(kvm, bus_idx);
875 if (bus)
876 bus->ioeventfd_count--;
877 ioeventfd_release(p);
878 ret = 0;
879 break;
880 }
881
882 mutex_unlock(&kvm->slots_lock);
883
884 eventfd_ctx_put(eventfd);
885
886 return ret;
887}
888
889static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
890{
891 enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
892 int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
893
894 if (!args->len && bus_idx == KVM_MMIO_BUS)
895 kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
896
897 return ret;
898}
899
900static int
901kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
902{
903 enum kvm_bus bus_idx;
904 int ret;
905
906 bus_idx = ioeventfd_bus_from_flags(args->flags);
907 /* must be natural-word sized, or 0 to ignore length */
908 switch (args->len) {
909 case 0:
910 case 1:
911 case 2:
912 case 4:
913 case 8:
914 break;
915 default:
916 return -EINVAL;
917 }
918
919 /* check for range overflow */
920 if (args->addr + args->len < args->addr)
921 return -EINVAL;
922
923 /* check for extra flags that we don't understand */
924 if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
925 return -EINVAL;
926
927 /* ioeventfd with no length can't be combined with DATAMATCH */
928 if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
929 return -EINVAL;
930
931 ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
932 if (ret)
933 goto fail;
934
935 /* When length is ignored, MMIO is also put on a separate bus, for
936 * faster lookups.
937 */
938 if (!args->len && bus_idx == KVM_MMIO_BUS) {
939 ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
940 if (ret < 0)
941 goto fast_fail;
942 }
943
944 return 0;
945
946fast_fail:
947 kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
948fail:
949 return ret;
950}
951
952int
953kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
954{
955 if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
956 return kvm_deassign_ioeventfd(kvm, args);
957
958 return kvm_assign_ioeventfd(kvm, args);
959}